1. Field of the Invention:
An electronic transducer in combination with a stethoscope for electronically monitoring the sounds which are mechanically produced by the stethoscope.
2. Description of the Prior Art:
Stethoscopes have long been used by physicians to monitor the various sounds produced by the heart. These stethoscopes typically consist of a mechanical sensor which is placed on the body of the test subject and which produce an acoustical wave in response to heart sound vibrations. The acoustical waves are transmitted through an air column contained in a flexible conduit to an earpiece inserted in the ear of the operator. As the sound wave exits the earpiece of the stethoscope, it is detected by the operator as a drumlike sound. The amplitude and frequency of the heart sounds have varying characteristics depending upon the physical condition and operation of the heart being tested. These instruments are commonly referred to as mechanical stethoscopes because they depend only upon mechanical means for the creation of the acoustical wave in response to the heart sounds.
Since mechanical stethoscopes were first developed, various attempts have been made to utilize electronic aids to enhance the monitoring of sounds which is carried out by the stethoscope. Such electronic aids have generally been used to either electronically amplify the sounds detected by the stethoscope and rebroadcast them to the stethoscope operator to aid him in his detection of heart sounds or to transmit the heart sounds as electronic signals to peripheral apparatus for such purposes as recording the heart sounds. In such devices, a microphone is typically utilized in combination with the stethoscope for picking up the acoustical wave which is transmitted through the stethoscope. The signals from the microphone are then either transmitted to the listener by means of a loudspeaker or transmitted directly to the peripheral equipment such as an oscilloscope or a recording instrument.
While these various electronic devices which have been developed for use with the stethoscope have been beneficial in that they enhance the output of the stethoscope, in each instance the electronic device has been designed such that its output is a substitution for the mechanically produced sound wave which normally is transmitted through the stethoscope to the ears of the operator. As a result, the electronic device, when in use, prevents the stethoscope user from simultaneously hearing the sound which was mechanically produced by the stethoscope. Such designs severely limit the usefulness of electronically aided stethoscopes currently available. This arises from the fact well known in the art that the sound which is "heard" by the listener when using a standard stethoscope with mechanically produced sound is different in form from electronically produced sound which is transmitted by the various electronic aids presently available. This difference in sound characteristic arises from the acoustics produced in the stethoscope when it is placed in the ears of the listener, including various reflections which are caused when the earpiece of the stethoscope is blocked off by its insertion in the listener's ear. As a result, the electrically reproduced sounds have a frequency and amplitude which is significantly different from that which is characteristically "heard" directly through the earpiece of the mechanical stethoscope. Thus, the sound "heard" by the listener through the electronic amplifying device is of a different form than that heard directly through the mechanical transmissions of the stethoscope. Because a physician or other person skilled in the use of the stethoscope becomes trained to hear certain sounds which are mechanically produced by the stethoscope, the electronically produced sounds represent a relatively foreign sound and are not accurately recognizable by the listener. For these reasons, when the electronic aid is substituted for the mechanical sound produced by the stethoscope, the stethoscope user cannot simultaneously use the stethoscope in a conventional manner to produce the mechanical sounds which are best known to the trained physician. If the person utilizing the electronically aided stethoscope for recording purposes wishes to himself listen to the heart sounds as they are produced mechanically through a stethoscope, he must either shut off the electronic aid or he must use a second stethoscope. Such operations may be very difficult because they require the handling of two pieces of equipment and both pieces of equipment cannot be placed over the exact area of the test subject body at the same time. In addition to being inconvenient, this lack of operating capacity in currently available electronic stethoscopes may produce a dangerous condition for the test subject. For example, if the heart sounds of a test subject are being electronically monitored with a presently available electronic stethoscope, the physician could not monitor the sounds himself while the electronic recording or transmitting was being accomplished. During this interval, the condition of the test subject could deteriorate considerably and perhaps dangerously.